Allow release package creation from gitlab-ci.yml

Problem to solve

Once #56022 is completed, we have a way to generate releases directly in the .gitlab-ci.yml. There's still one big piece missing, however - the ability to create the release binary package itself and put it somewhere that it can be downloaded.

Target audience

TBD

Further details

TBD

Proposal

Allow specifying a local set of files that can be created as a release archive, then make it available at some standard URL within the project.

In the existing implementation (#56022), building the release package and uploading it somewhere is up to the user (see enumerated steps in script section):

In this example, the job would know how to create a zipfile containing everything in the output/release folder, and name it with the appropriate filename and extension. We should allow any file format supported for the source code. The file would be automatically uploaded to a repository and a release would be created with a pointer to that URL. The job would then replace the packages section in the yaml with a link and make the appropriate API call to the Release API.